1. Field
Exemplary embodiments relate to an atomic layer deposition apparatus, and more particularly, to an atomic layer deposition apparatus that may simultaneously load and unload a plurality of substrates to improve a throughput.
2. Description of the Related Art
In general, to deposit a thin film with a predetermined thickness on a substrate such as a semiconductor substrate, a glass, and the like, there may be used a method of fabricating the thin film utilizing a physical vapor deposition (PVD) using physical collision such as sputtering, a chemical vapor deposition (CVD) using chemical reaction, and the like.
As a design rule of a semiconductor device becomes rapidly minute, a thin film with a minute pattern is required, and a step, on which the thin film is formed, may become significantly great. Accordingly, an atomic layer deposition (ALD) that may significantly and uniformly form a minute pattern with an atomic layer thickness and have excellent step coverage has been increasingly used.
In terms of using chemical reaction between gas molecules, the ALD may be similar to a general CVD. However, unlike the general CVD that may simultaneously inject a plurality of gas molecules into a process chamber, and deposit, on a substrate, a reaction product generated from an upper portion of the substrate, the ALD may inject a single gas element into the process chamber to purge the injected gas element, allow only a physically deposited gas to remain on a surface of a heated substrate, and inject other gas elements into the process chamber to thereby deposit a product of chemical reaction generated on the surface of the substrate. A thin film realized through the ALD may have an excellent step coverage property and a low impurity content and thus, is currently widely used.
As for an existing ALD apparatus, there is disclosed an ALD of a semi-batch type in which a deposition process is simultaneously performed on a plurality of substrates to improve a throughput. In general, the ALD apparatus of the semi-batch type may be performed such that different deposition gases are injected and a substrate sequentially passes through an area where the deposition gases are injected by means of a high-speed rotation of a gas injection unit or susceptor unit, and a product of a chemical reaction between the deposition gases is deposited on the surface of the substrate to thereby form a thin film.
Here, in the existing ALD apparatus, two process chambers of the semi-batch type are provided to perform a deposition process simultaneously with respect to 12 pieces of substrates. The ALD apparatus may include a transfer robot that may transport a substrate from a buffer to the process chamber, and load and unload the substrate on the process chamber. Here, an existing transfer robot may load/unload and transport the substrate one by one, and one transfer robot may be generally provided due to spatial limitations of the ALD apparatus.
However, in the existing ALD apparatus, since one transfer robot serves to load/unload and transport the substrate, a time required for loading/unloading and transporting the 12 pieces of the substrate may be great. When a time is delayed in the transfer robot while loading/unloading and transporting the substrate, a time delay may occur during the deposition process to thereby reduce throughput and productivity. Also, in the buffer, 25 pieces or 50 pieces of substrates are generally stored, however a process module may perform the deposition process with respect to 12 pieces of the substrates, so that extra substrates may remain. As a result, a time required for replacing the buffer and supplementing the substrate may be needed due to treatment of the extra substrates.